Vaginal Mesh: Class Actions, Trials and Tribulations

Posted by Professor Mike O’Connor AM on 9 September 2019
Vaginal Mesh: Class Actions, Trials and Tribulations

More than 6 percent of people in first world countries have received an implantable medical device "for rebuilding body functions, achieving a better quality of life, or expanding longevity" and 1.7 million patients have been injured worldwide from 2005 to 2014. Nevertheless the innovations and continual improvements in medical devices mean that a majority of patients have received great benefit from these implants.

Up to 15% of women recipients of vaginal mesh experienced vaginal bleeding, discharge and vaginal discomfort resulting from the protrusion of the mesh through the overlying vaginal skin. An Australian class action against a major surgical supplier by over 800 women suffering from complications of vaginal mesh repair has been underway in the Federal Court since 4 July 2017.Her Honour has yet to deliver her determination. The majority of the 800 patients in the class action are suffering severe vaginal/pelvic pain and many have experienced mesh erosion /exposure.

A critical question raised in the Trial was why the vaginal implantation of foreign material was introduced with so little prior assessment of its safety.

Vaginal mesh was introduced in the late 1990's, initially in thin bands 7 mm in width placed underneath the mid portion of the urethra to cure urinary incontinence. It proved to be highly successful in curing urodynamic stress incontinence with long term cures of up to 92%. That experience informed the TGA deliberations on vaginal prolapse mesh implantations.

In 2015 a Dutch journalist Jet Schouten in cooperation with Professor Carl Heneghan an Oxford University expert in evidence based medicine, submitted a scam proposal to the Austrian branch of TUVan EU assessor-to approve a vaginal mesh that is normally used to package mandarins for use in humans. It received a tacit approval from TUV. The TGA relies on international agencies for much of its device assessments.

Klinge et al in 1999 evaluated a remarkable number of explanted meshes and found that the mesh porosity was the most important determinant of the tissue reaction and risk of scar entrapment. The pore size must be much larger than 75 microns to preserve tissue integration without filling the pores with scar tissue. Mesh contraction, which ultimately occurs in more than 25% of patients over time, is another cause for vaginal symptoms such as pain.

Biofilm: bacterial contamination of mesh

A biofilm refers to complex communities of bacteria residing within an exopolysaccharide matrix that adheres to a mesh surface. Colonisation of vaginally implanted mesh occurs frequently: in a study by Vollebregt et al in 2009, 83.6% of a series of vaginal mesh implants in 64 consecutive women were found to be contaminated with bacteria at the time of implantation. They were admittedly in low bacterial densities, irrespective of the sterility of the surgery.

There is a close correlation between chronic inflammation due to a foreign body and low grade chronic infection. Experience with other foreign body mesh insertions suggest that bacterial colonisation in the biofilm around implanted material may lead to low grade chronic infections. Host tissue erosion and mesh migration are very likely to be linked to contamination with microorganisms such as bacteria and fungi, with or without biofilm formation.

Characteristics of the Ideal Mesh

The ideal tissue substitute for prolapse repair is biocompatible, inert, inexpensive, induces minimal inflammatory response and, at the same time, acts as a scaffold to facilitate fibrous tissue ingrowth, is resistant to infection, avoids shrinkage and is easy to handle. The mesh should incur minimal inflammatory reaction and be followed by vascular and fibroblastic ingrowths. The key factors for host response to synthetic meshes are pore size and weave. The pore size must be much larger than 75 microns to preserve tissue integration without filling the pores with scar tissue. A pore size > 1 mm is required for prolapse, and the pore size should be > 3 mm in cases of mechanical strain. Meshes with large pores exhibit less inflammatory infiltrate, connective tissue, fistula formation, calcification, and bridging (i.e., the pores are filled by scar tissue) than meshes with small pores.

Abdominal Mesh Hernia Repairs: failure to appreciate mesh complications

The use of mesh for abdominal hernias especially inguinal hernias and incisional hernias commenced in 1958 when Usher et al published their technique using Marlex a material which because of its large pores, allowed granulation tissue to grow through it. Over time, fibroblast activity increased, more collagen was deposited without giant cells and the repair increased in strength over a 12 month period. Usher in 1963 reported the use of polypropylene mesh (a mono-filamentous polymer) for mesh abdominal herniorrhaphies. By 2003 it was apparent that mesh hernia repairs could cause significant chronic pain mediated by a foreign body reaction including inflammation, fibrosis, calcification, thrombosis or infection. The proportion of recipients who developed chronic pain was 'high' and typically presented more than 12 months after the herniorrhaphy. A syndrome of 'mesh inguinodynia' chronic pain at the site of mesh inguinal hernia repair was described in 1998. Narrow pore size and heavy fibre content were at that time implicated in the production of chronic pain. Light weight mesh products with large pore size (>1 mm) and elasticity of 25-35% at 16 Newtons per cm produced significantly reduced rates of chronic pain. This introduction of lightweight mesh for herniorrhaphies was motivated by a desire to 'restor[e] the abdominal functions and be integrated physiologically into the abdomen based on a maximum of biocompatibility'.

Australian response to vaginal mesh

In Australia the TGA decided on 28 November 2017 to remove transvaginal mesh products whose sole use is the treatment of pelvic organ prolapse by implantation from the Australian Register of Therapeutic Goods (ARTG). This effectively deprived gynaecologists of using vaginal mesh. Since the review commenced in 2013, 45 devices have been removed from uro-gynaecological use by the TGA - 43 cancelled from the ARTG and a further two have been limited to non-uro-gynaecological procedures. The TGA also responded to the concerns regarding the insertion of vaginal mesh by reclassifying such devices from Class II b (medium to high risk) to Class III (high risk) in December 2018.

End users (surgeons) have the obligation to be fully apprised of the characteristics of implanted products. This should guide the selection of mesh product and the selection of patients who could benefit from mesh implants. Surgeons also have the obligation to ensure that the surgical skills with which they implant mesh are conscientiously learnt and upgraded regularly. The designers, manufacturers and regulatory bodies for medical devices are reliant on surgeons for clinical research especially audits of mesh recipients' complications and efficacy. That information is critical for patient safety.

From a surgical perspective it seems likely that vaginal mesh will be abandoned in favour of laparoscopic abdominal colpopexies or vaginal sacrospinous fixations.

Further reading:

  1. Johnson & Johnson / Ethicon Class Action
    https://www.shine.com.au/service/class-actions/johnson-johnson-ethicon-class-action retrieved 19 July 2019
  2. Klinge U, Klosterhalfen B, Muller M, Schumpelick V. Foreign body reaction to meshes used for the repair of abdominal wall hernias. Eur J Surg. 1999;165:665673
  3. Ford AA, Rogerson L, Cody JD, Aluko P, Ogah JA. Mid-urethral sling operations for stress urinary incontinence in women. Cochrane Database of Systematic Reviews 2017, Issue 7. Art. No.: CD006375. DOI: 10.1002/14651858.CD006375.pub4
    https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006375.pub4/epdf/full retrieved 21 July  2019
  4. Atherton M, Daborn J, Tsokos N, Jeffery JT, Yin M. Complications associated with tissue anchor migration after vaginal surgery using the tissue fixation system a case series. Australian and New Zealand Journal of Obstetrics and Gynaecology 2012; 52:83-86.
  5. Maher C, Feiner B, Baessler K, ChristmannSchmid C, Haya N, Marjoribanks J. Transvaginal mesh or grafts compared with native tissue repair for vaginal prolapse. Cochrane Database of Systematic Reviews 2016, Issue 2. Art. No.: CD012079. DOI: 10.1002/14651858.CD012079.
  6. Scandal of fruit netting 'approved as surgical implant'(London, Sunday Times Jan 11.2015)
    https://www.thetimes.co.uk/article/scandal-of-fruit-netting-approved-as-surgical-implant-dvcqd2rt9mr retrieved 25 August 2019
Posted in: Medicolegal  

Errors in Antenatal Genetic Diagnosis and Wrongful Therapeutic Abortion

Posted by Dr Mike O'Connor on 5 June 2019
Errors in Antenatal Genetic Diagnosis and Wrongful Therapeutic Abortion

In November 2018 a 39 year old IVF patient of mine received terrible news that her Non Invasive Prenatal Test at 11 weeks was positive for Trisomy 13.

Patau syndrome is associated with severe intellectual disability and a range of physical defects including heart abnormalities, cleft lip, microphthalmia, brain and spinal anomalies. Only 10% or less of such infants survive until the second year of life. 

Needless to say many mothers would request a therapeutic abortion when given that diagnosis and this was certainly an option for my patient.

Some wise advice was given to me by a geneticist who recommended that the NIPT diagnosis be confirmed by genetic amniocentesis. That took another 5 weeks of agonising wait for the patient however the result showed a NORMAL karyotype. Thankfully I was spared the embarrassment of terminating a eukaryotic fetus. 

In May this year a Dublin woman was not so lucky when she had a termination for a trisomy 18 (Edwards syndrome) at the National Maternity Hospital - normally a very conservative obstetric hospital. It was thought the baby had Trisomy18, also known as Edwards Syndrome, but a series of genetic tests later found that that was not the case.

Edward syndrome is due to Trisomy 18 and is associated with intrauterine growth restriction, congenital heart disease, a small, abnormally shaped head; a small jaw and mouth; and clenched fists with overlapping fingers. It is associated with stillbirth. Some survive and in Ireland there are teenagers living with the disorder.

In an interview with RTE news radio on 17 May 2019 the Master of the Rotunda Hospital in Dublin (my alma mater) explained that NIPT tests should be confirmed by CVS or genetic amniocentesis. Prof Fergal Malone also noted that the karyotype may differ between fetus and placenta.

Accuracy of NIPT tests for Trisomies

  1. 82% of T21 positive results will have Down Sydndrome
  2. 49% of T18 positive results will have Edward syndrome
  3. 37% of T13 positive results will have Patau syndrome

This means that all NIPT positive trisomy findings  should be confirmed either by CVS or genetic amniocentesis.

 

Trisomy 13 occurs in about 1 in 16,000 newborns

 

Trisomy 18 occurs in about 1 in 5,000 live-born infants

Further Reading:

  1. Taylor-Phillips S, Freeman K, Geppert J, et al Accuracy of non-invasive prenatal testing using cell-free DNA for detection of Down, Edwards and Patau syndromes: a systematic review and meta-analysis BMJ Open 2016;6:e010002. doi: 10.1136/bmjopen-2015-010002
  2. Mersy E, Smits LJ, van Winden LA, et al. Non-invasive detection of fetal trisomy 21: systemat ic  review and report of quality and outcomes of diagnostic accuracy studies performed be tween 1997 and 2012. Hum Reprod Update 2013;19:31829. doi:10.1093/humupd/dmt001
  3. Verweij EJ, van den Oever JM, de Boer MA, et al. Diagnostic accuracy of non-invasive detec tion of fetal trisomy 21 in maternal blood: a systematic review. Fetal Diagn T her 2012;31:81 6. doi:10.1159/000333060
Posted in: Obstetrcis  

Menstrual Cups and Toxic Shock

Posted by Professor Mike O’Connor AM on 10 December 2018
Menstrual Cups and Toxic Shock

Menstrual cups are flexible silicone or rubber cups which are applied to the upper vaginal fornices to collect menstrual blood. They are increasingly being used as a more environmentally-friendly alternative to tampons. They are intended for re-use and can last for upwards of 10 years. Whereas the monthly cost of tampons is ~$10  (before the lifting of GST soon) a menstrual cup costs between  $35-50.

At a recent tutorial at WSU I found that 50% of the women students preferred a menstrual cup to tampons. This may be a cost issue but other reasons include a belief that menstrual cups are safer. That is not correct.

Toxic shock syndrome has been recently described in a woman using a menstrual cup. The woman described sustaining a small abrasion during insertion and 7 days later developed abnormal bleeding with a brown discharge followed 2 days later by a purulent discharge and fever. Over the next 24 hours she became hypotensive with a tachycardia and high fever. She was treated with IV clindamycin. She developed a generalized morbilliform rash.

Toxic shock syndrome is now rarely seen however it was described in 1980 in the Lancet and the 2 main risk factors were the use of high-absorbency tampons and prolonged, continual usage.

The classic causative organism was Staph aureus although Streptococcus can also cause toxic shock syndrome.

Common risks

This common risk of tampons and menstrual cups may depend on the following features of menstrual cups:

  • Accumulation of blood in the silicone material.
  • Increased vaginal pH with use of cups.
  • Presence of O2 and CO2 in vagina during the use of menstrual cups.

Because of accumulation of blood, menstrual cups appear to provide a medium for bacterial growth with the same three conditions mentioned above. Menstrual blood emanating from the uterus is sufficient to promote the growth of S. aureus in the lower genital tract.

The current incidence of toxic shock syndrome is 1:100,000.

High placement of a contaminated cup, an abundant volume of menstrual blood and mucosal irritation within the vagina may be considered as other probable contributing factors.

The very real reduction in toxic shock with tampons over the past 20 years can be mainly attributed to changes in the absorbency and composition of tampons available to the consumer. The removal of the RelyTM brand in the US which featured high absorbency was an important improvement in safety.

Toxic shock is well named as it is caused by an exotoxin (toxin 1 :TSST-1) released from Staph aureus.

Advice about the use of menstrual cups:

  1. Use for no more than 6-8 hours at a time (the volume capacity is 30 mls).
  2. Don't leave a menstrual cup in situ overnight.
  3. Wash cup carefully between uses (however this may not be sufficient for asepsis).
  4. Wash hands carefully before insertion.
  5. If the patient develops a fever, a rash or syncope then urgent medical attention should be sought.

Further reading:

  • Mitchell MA,Bisch S,Arntfield S,Hosseini-Moghaddam S A confirmed case of toxic shock syndrome associated with the use of a menstrual cup Can J Infect Dis Med Microbiol. 2015 Jul-Aug; 26(4): 218220.
  • Schuchat A, Broome CV.Toxic shock syndrome and tampons Epidemiol Rev. 1991;13:99-112.
  • Helgerson SD. Toxic-shock syndrome: tampons, toxins, and time: the evolution of understanding an illness.Women Health. 1981 Fall-Winter;6(3-4):93-104.
  • Bonventre PF1, Heeg H, Cullen C, Lian CJ. Toxicity of recombinant toxic shock syndrome toxin 1 and mutant toxins produced by Staphylococcus aureus in a rabbit infection model of toxic shock syndrome.Infect Immun. 1993 Mar;61(3):793-9.
Posted in: Obstetrcis  

Reproductive Aspects of Acute Appendicitis

Posted by Professor Mike O’Connor AM on 26 July 2018
Reproductive Aspects of Acute Appendicitis

Introduction

Appendicitis most often occurs between the ages of 10 19 years, with an incidence of between 19-28 per 10,000 before the age of 14 years. Less than 7 per 10,000 children present with appendicitis before the age of 4 years & less than 5% of presentations with appendicitis occur before the age of 5 years. 

Causation 

In tropical climates the cause is often a parasitic worm (pinworm or roundworm) causing obstruction whereas in temperate climates the cause of obstruction of the appendix is more likely to be mechanical twisting or lymphoid hyperplasia associated with viruses such as adenovirus and rubeola or an endoluminal faecolith or undigested food. Periumbilical pain signifies appendiceal colic associated with the obstruction.

As part of the obstruction the lumen of the appendix increases in diameter and this is the basis of the ultrasonic diagnosis of appendicitis: the diameter exceeds 6 mm.

The proliferation of bacteria results in penetration of the wall of the appendix which becomes inflamed and gangrenous. When the pain moves to the right iliac fossa and becomes constant then inflammation of the appendix is underway. Perforation occurs rarely in the first 12 hours of symptoms but is more likely with time thereafter, becoming common after 72 hours. 

Generalized peritonitis develops if the infection is not contained by bowel loops and omentum.

Delays in Diagnosis in Young Girls

Prior to rupture there appears to be no effect of appendicitis on tubal function however when the diagnosis is delayed and perforation has already occurred at the time of surgery tubal damage is increased (Relative Risk =4.8;95% CI =1.5-
14.9).

Future Risk of Ectopic Pregnancy

There appears to be a significantly increased risk of ectopic pregnancy in women who have appendicitis. In one study Elraiyah et al found the risk to be (OR=1.78,95% CI=1.46-2.16). A study by Fernandez et al found a similar increase in the risk of ectopic (RR= 2.2 ;95 percent CI: 1.5-3.2 ) but there appeared to be no difference in the ectopic rate between ruptured and unruptured appendices.

Appendicitis in Pregnancy

In a classic case of appendicitis in pregnancy Tthe pain is periumbilical & colicky initially and then migrates to the right lower quadrant as a constant pain as the inflammatory process progresses Anorexia, nausea and vomiting, if present, follow the onset of pain. Fever up to 38.3ºC and leukocytosis develop later. Many patients have a nonclassical presentation, with symptoms such as heartburn, bowel irregularity, flatulence, malaise, or diarrhea. If the appendix is retrocecal, patients often complain of a dull ache in the right lower quadrant rather than localized tenderness. Rectal or vaginal examination in such patients is more likely to elicit pain than abdominal examination. A pelvic appendix can cause tenderness below McBurney's point. The most common symptom of appendicitis, ie, right lower quadrant pain, occurs close to McBurney's point in the majority of pregnant women, regardless of the stage of pregnancy however, the location of the appendix migrates a few centimeters cephalad with the enlarging uterus, so in the third trimester, pain may localize to the mid or even the upper right side of the abdomen (see figures)

   

Investigations

  1. WCC. Approximately 80 percent of nonpregnant patients with appendicitis have a preoperative leukocytosis (white cells >10,000 cells/microL) and a left shift in the differential. However, mild leukocytosis can be a normal finding in pregnant women: the total leukocyte count may be as high as 16,900 cell/microL in the third trimester.
  2. Ultrasound of Appendix. The initial modality of choice for diagnostic imaging of the appendix in pregnancy is graded compression ultrasonography. The clinical diagnosis of suspected appendicitis is supported by identification of a non-compressible blind-ended tubular structure in the right lower quadrant with a maximal diameter greater than 6 mm.
  3. MRI .For pregnant women whose ultrasound examination is inconclusive for appendicitis, magnetic resonance imaging (MRI) is the preferred next test as it avoids the ionizing radiation of computed tomography and appears to be cost-effective

Obstetric Consequences of Acute Appendicitis in Pregnancy

The main complication is threatened preterm labour. In one study contractions occurred in 83% of all appendicitis patients in pregnancy >24 weeks with 13% exhibiting changes in cervical dilatation. The advent of laparoscopic appendicectomy has encouraged earlier diagnosis and treatment. Delayed diagnosis can have dire adverse effects on the fetus due to prolonged sepsis.

Further Reading

  1. Mueller BA et al.Appendicectomy and the risk of tubal infertility. NEJM 1986.315:1506-1508
  2. Elraiyah T et al. The effect of appendectomy in future tubal infertility and ectopic pregnancy: a systematic review and meta-analysis. J Surg Res 2014.192(2)368-374
  3. Fernandez et al. Appendectomy, a risk factor for ectopic pregnancy La Presse Medicale 1992 21(39):1859-1861.
  4. Williams R, Shaw J Ultrasound scanning in the diagnosis of acute appendicitis in pregnancy. Emerg Med J. 2007 May;24(5):359-60
Posted in: Obstetrcis Ultrasound Other  

NIPT screening & Nuchal Translucency - Complimentary rather than alternatives

Posted by Professor Mike O’Connor AM on 2 May 2018

The advent of the Non Invasive Prenatal Test has been a major advance for the detection of Trisomy 21 (Down s.), Trisomy 18 (Edwards s.) & Trisomy 13 (Patau s.) and reduces the need for invasive tests which have up to a 3% risk of miscarriage.

There has been a subsequent tendency to abandon the previous nuchal translucency ultrasound and biochemical test because of the increased accuracy of detection of the trisomies with the NIPT test which can detect 99% of Down syndrome fetuses c.f. a 90% detection rate with NT Plus.

What seems to be less well appreciated is that the NIPT does not provide a full karyotype as it relies on frag-ments of fetal DNA within maternal blood .These are then used to detect T211,T18 or T13 using specific probes. More recently a further probe is availa-ble to detect 22 q deletions as found in DiGeorge syndrome: a complex syndrome involving cardiac ,facial, skeletal and neurological abnormalities which has an incidence of 1/1000.

Reliance on an NIPT to exclude a fetal aneuploidy is unsound and a positive NIPT will still require confirmation using genetic amniocentesis or CVS. The value of a nuchal translucency test between 11-13 weeks is that it will give additional information not available with an NIPT test.

For example, the nuchal translucency is not just increased (>3 mm) in fetal aneuploidies such as Down syndrome and Turner's syndrome (45 XO) but is also increased in fetal cardiac malformations: more than 55% of all major congenital heart defects in one series (Hyett et al 1999) had an NT > 95 per-centile (NR 1.8-2.35 mm) and the negative predictive value of a normal NT was 99.9%.

Furthermore a careful ultrasound scan at 11-13 weeks can give additional information such as cervical length ( values <3 cm can predict cer-vical incompetence) as well as basic information such as cranial anatomy (eg excluding anencephaly), spine, stomach, kidneys, bladder & presence of all 4 limbs. These non-cardiac features can be reasonably assessed in between 75-98% of cases between 11-14 weeks. Other important ultrasound findings at 11-13 weeks include detection of uterine fibroids and ovarian tumours which may cause complications such as red degeneration and torsion respectively later in pregnancy.

Fetal morphology scans: diagnostic value and limitations especially fetal heart anomalies

The fetal morphology scan is normally performed between 18-20 weeks gestation. If performed by skilled ultrasonologists it will detect a significant number of serious fetal anomalies. It is important to remember that only about one third of structural abnormalities are associated with an abnormal karyotype. The basic information available includes:

  1. An assessment of gestational age (+/- 7-10 days error)
  2. An assessment of fetal morphology
  3. An assessment of placental localization (bearing in mind that the vast majority of 'low lying' placentae will not remain so by term)

Approximately 1% of liveborn fetuses have congenital heart disease (CHD). What is concerning is the failure to diagnose a large number of these fetuses with (CHD) at that gestational age. A little later at 22 weeks there is a better yield of diagnoses of CHD.

The 1993 RADIUS study surveyed 92 obstetric practices and 17 family practices in 6 US States and identified 15,530 low risk pregnant women who were scanned between 15-22 weeks and 31-35 weeks by 28 ultrasound referral laboratories staffed by 91 qualified sonologists. Of those women (whose fetal anomaly rate was 2.3%) only one third had one (or more) major fetal anomalies detected by 24 weeks. It demonstrated that few of the CHD's were detected .No improvement in overall perinatal outcome could be demonstrated. 

More recently one US study (Pinto et al, 2011) over a 10 year period found that only only 39% of 1474 cases of significant CHD were detected, with no improvement in detection rate over the 10year period. Detailed fetal echocardiography can improve the detection rate but this is impractical for large populations. The 4 chamber cardiac scan is the basic standard and this will miss defects such as transposition of the great arteries (TGA), tetralogy of Fallot (TOF), double-outlet right ventricle (DORV) and truncus arteriosus. The 4 chamber view cardiac view is likely to identify complete atrioventricular septal defect (AVSD), congenitally corrected transposition of the great arteries (CCTGA), tricuspid valve disease (including Ebstein's anomaly) and all single ventricle defects including hypoplastic left heart syndrome (HLHS). A circumspect approach is therefore required when receiving a normal fetal morphology scan result.

Further reading:

  • Alldred SK et al. First trimester ultrasound tests alone or in combination with first trimester serum tests for Down's syndrome screening.Cochrane Database Syst Rev. 2017 Mar 15;3:CD012600. doi: 10.1002/14651858.CD012600.
  • Sharifzadeh M et al. Normal reference range of fetal nuchal translucency thickness in pregnant women in the first trimester, one center study J Res Med Sci. 2015 Oct; 20(10): 969973.
  • Hyett J,Perdu M,Sharland G, Snijders R,Nicolaides K. Using fetal nuchal translucency to screen for major congenital cardiac defects at 10-14 weeks of gestation: population based cohort study BMJ. 1999 Jan 9; 318(7176): 8185.
  • Pinto NM et al. Barriers to prenatal detection of congenital heart disease: a populationbased study Ultrasound Obstet Gynecol. 2012 Oct;40(4):418-25. doi: 10.1002/uog.10116. Epub 2012 Sep 17.
  • Ewigman BG et al. Effect of prenatal ultrasound screening on perinatal outcome. RADIUS Study Group.N Engl J Med. 1993 Sep 16;329(12):821-7.
Posted in: Obstetrcis Ultrasound Miscarriage  
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