Behind The Medical Headlines

NEW PATIENT/PUBLIC SUMMARY ARTICLE No.3 (pilot): Fetal interventional surgery

• Mr G McAlister, adapted from the original clinical review article by Dr Ross Welch and Mr Leon Dupuch, Derriford Hospital, Plymouth, UK

Summary

We are currently piloting the production of plain English ‘Patient/Public’ summaries of original clinical review articles published on the BTMH website in order to increase public access to, and understanding of, the clinical content of these articles. Please access this short Patient/Public summary of Dr Welch and Mr Dupuch’s overview of fetal surgical intervention and complete the short survey at the end of this article in order to provide us with your feedback.

Declaration of interests: No conflict of interest declared

Patient/public version of article

Fetal surgical intervention

(Adapted from the original clinical article by Dr Ross Welch and Mr Leon Dupuch. Dr Ross Welch is a Consultant in Fetal Medicine and Mr Leon Dupuch a Specialist Registrar in Obstetrics and Gynaecology at Derriford Hospital, Plymouth, UK)

Introduction

A number of complications can occur as a fetus (baby) develops inside the womb. In some cases these complications can be life-threatening or lead to serious disease if untreated, and require urgent medical intervention. While pre-term fetuses can be delivered early in order to enable such medical treatment, the chances of a fetus’s survival are lower the earlier the delivery occurs (read our related article When is the ideal time to deliver a pre-term fetus?for further information regarding this). In cases where it is considered that a fetus would not survive early delivery, some emergency surgical procedures have been developed to enable surgery on the fetus while it is still inside the womb.

Fetal blood transfusion

Fetal blood transfusion can be required when a mother passes antibodies to the fetus and the fetus gains an immunity against its own cells. Such transfusions use special transfusion blood and can be performed either through the blood vessels or through the peritoneum (the membrane lining the abdominal cavity). Developments have also taken place that enable medical staff to test for fetal blood abnormalities by testing the mother’s blood samples, rather than having to take blood samples directly from the fetus – a procedure that would carry greater risk to the fetus.

Fetal shunting

By far the most common, and widely tested, procedure is fetal shunting. Pleuro-amniotic shunting involves inserting a tube between the chest and the amniotic cavity while the fetus is inside the womb, to draw excess fluid from the chest. Vesico-amniotic shunting involves inserting a tube into the fetus’s bladder to draw excess fluid into the surrounding area.

Acardiac twinning

Acardiac twinning is a rare complication in identical twins in which one fetus develops normally, but the other fetus’s heart does not develop properly. The abnormal fetus’s heart can be absent or only partially formed, resulting in the fetus’s non-development. In such cases abnormal blood vessels in the placenta result in the normal fetus pumping blood through the tissue of the abnormal fetus. This carries a high risk of heart failure for the normal fetus, as its heart is being overworked. The normal fetus can be saved by removing an artery from the umbilical cord (a procedure known as acardiac twin ablation of blood supply) and stopping the blood supply to the partially formed fetus. This procedure can be carried out either by using a laser or ultrasound guided diathermy (the use of a high frequency electrical current to produce heat and destroy the tissue).

Twin-to-Twin Transfusion Syndrome

In this syndrome blood flows from one identical twin to another, sharing a placenta. This leads to an imbalance of circulating blood and amniotic fluid (the fluid in the womb that surrounds the fetus and protects it from external pressure). The syndrome can cause heart and growth problems, and has a high death rate if untreated. Considerable progress has, however, been made by developing procedures involving the removal of amniotic fluid, the creation of a hole in the membrane separating the twins to balance fluid levels and removing blood vessels from the placenta.

Other procedures

Fetal surgical intervention has been performed in some less well-tested areas including the ‘repair’ of spina bifida (based on the theory that exposure of the spinal nerve material to amniotic fluid causes progressive damage the longer the fetus remains in the womb), fetal heart disease and the removal of fetal tumours.

While there is strong evidence of the effectiveness of fetal transfusion and fetal shunting, these other procedures are all currently being assessed for effectiveness.

Despite the progress made in fetal interventional surgery the biggest remaining problem is how to prevent the leakage of amniotic fluid from the womb after the procedure has been carried out, which leads to the early delivery of the fetus. Developments intended to reduce this risk include the use of smaller surgical instruments, the use of contraction-stopping drugs and the development of the amniopatch procedure that seeks to seal the hole in the womb.

The future

It is hoped that fetal interventional surgery may, in future, be used for the treatment of a number of diseases, including cystic fibrosis and Huntingdon’s disease.

Further information

National Institute for Health and Clinical Excellence Insertion of pleuro-amniotic shunt for fetal pleuro effusion – Information for the public

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