Serial Amniocentesis

TTTS. Serial Amniocentesis

Amniocentesis is the standard screening technique for fetal anemia, because amniotic fluid contains hemolytic products excreted from the fetal kidneys and lungs, including bilirubin.

Amniocentesis (also referred to as amniotic fluid test or AFT) is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, and also for sex determination, in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the amniotic sac surrounding a developing fetus, and then the fetal DNA is examined for genetic abnormalities. 

The most common reason to have an "amnio" is to determine whether a baby has certain genetic disorders or a chromosomal abnormality, such as Down syndrome. Amniocentesis (or another procedure, called chorionic villus sampling (CVS)) can diagnose these problems in the womb. Amniocentesis is performed when a woman is between 14 and 16 weeks gestation. 

Women who choose to have this test are primarily those at increased risk for genetic and chromosomal problems, in part because the test is invasive and carries a small risk of miscarriage. This process can be used for prenatal sex discernment and hence this procedure has legal restrictions in some countries. Amniocentesis was first introduced by American obstetrician Fritz Friedrich Fuchs and Danish gastroenterologist Polv Riis in 1956 for fetal sex determination and up to mid 1970s amniocentesis were done 'blind‘. 

Septostomy

TTTS. Septostomy

The rationale on the use of septostomy or dividingmembrane amniorrhexis for the treatment of TTTS was to equilibrate the amniotic pressures on both sides of the membrane.10,11 Prior to its proposal, a difference in amniotic fluid pressures in the two sacs was never demonstrated. 

On the contrary, Quintero and others showed that, in fact, the pressure in both sacs is similar.12,13 Notwithstanding, a randomized controlled trial was carried out to compare septostomy versus amnioreduction.14 The study was terminated at the planned interim analysis stage after 73 women were enrolled. 

Medical Treatment

TTTS. Medical Treatment

Medical treatment of TTTS has included only isolated case reports involving the use of digoxin3–5 or indomethacin.6–8 The rationale for the use of digoxin is to treat a recipient twin in heart failure. 

Relatively high maternal serum levels of digoxin must be achieved in order to reach therapeutic levels in TTTS, as the mean feto–maternal gradient is 0.56.9 Fetal levels are also directly related to GA. 

An evidence-based analysis

Treatment of twin–twin transfusion syndrome: an evidence-based analysis

Management of twin–twin transfusion syndrome (TTTS) has encompassed a wide spectrum of options, including expectant management, medical therapy, and surgery, as well as pregnancy termination. 

Over the past few years, significant emphasis has been given to the development of clinical practice guidelines that are derived from evidence-based medicine. 

Results

Twin to Twin Transfusion Syndrome. Results

Between July 1997 and June 2002, 252 patients with the diagnosis of TTTS underwent surgical treatment at our center. UCO was performed on 36 (14.3%) of these patients. Ten cases were excluded from the analysis because they had undergone secondary UCO after an attempted SLPCV (technical success rate for TTTS 216/226, or 95.5%). 

One additional case was excluded because the ligated cord was that of a recipient twin that had died shortly before surgery. Thus, 25 cases of TTTS underwent primary UCO. Six (24%) had cord occlusion of the donor fetus (donor group) and 19 (76%) of the recipient fetus (recipient group). Six fetuses had the following discordant fetal malformations: 2 had neural tube defects (both donors), 1 had body-stalk anomaly (donor), 1 had pulmonary atresia (recipient), 1 had anencephaly (recipient), and 1 had intracranial hemorrhage (recipient). 

Surgical technique

Twin-Twin Transfusion Syndrome. Surgical technique

The two methods of cord occlusion performed were umbilical cord ligation (UCL) or umbilical cord photocoagulation (UCP). UCL was performed via a 3.5 mm trocar inserted percutaneously into the amniotic cavity via 1–2 mm skin incision under continuous ultrasound guidance and general or local anesthesia. 

The cord of the target fetus was identified endoscopically with a 2.7–3.3 mm diagnostic or operating endoscope (Richard Wolf, Inc., Vernon Hills, IL, USA). A 3-0 Vicryl suture that had been previously threaded through a custom-designed knot-pusher was passed down the working channel of the endoscope with a semi-automatic grasper (Cook Ob/ Gyn, Spencer, IN, USA), or through a second port, and was laid underneath the target umbilical cord. 

Methods

TTTS. Methods

Standard sonographic diagnostic criteria for TTTS included polyhydramnios in the recipient twin (maximum vertical pocket [MVP] ?8 cm), oligohydramnios in the donor twin (MVP ?2 cm), single placenta, same gender, and thin-dividing membrane with absent ? or twin-peak sign. 

Each case was prospectively classified using the Quintero staging system,15 as described in Chapter 7. Primary UCO was offered if there was (1) presence of a lethal discordant fetal anomaly, or (2) stage III/IV in a patient who elected this modality.