P1130037

Front Day 40 even in unilateral twin pregriancics the iwo fetoses may be so far apait that it may be difficult to capture botfa on a single ułtrasound image (Fig. 1.78).

In advanced gestatkm (2nd and 3rd trimesters) it is difficult to diagnose twin pregnancies by transrectal ul-trasooography. Sometimes it is possible to see two fe-nses (Fig. 1.79). Wherc this is possible the existence of a twin pregnancy can be confirmed. Should oniy one fetus be detectabie making a diagnosis of a confirmed seisjeton should be approached wńh caution.

1.3.2.6 Transvaguial sonographic puncture of the conceptus

Since the manuał reduction of a twin pregnancy is usualh not successfuł after Day 20 to 25, the possibility of efiminating one conceptus by oontrolled puncture was considered. It appeared promising to puncture one conceptus under visua] control of a vaginal!y introduced ułtrasound probe.

For this purpose a pistoł-like instrument was de-signed. The barrel of the instrument accommodates the ułtrasound probe and on the handle is a trigger for the automated puncture deyice (Fig. 1.80). The handle of the vaginal sector probe is fixed within the tip of the bar-reL A spring mechanism is used to drive the punctuńng needle and an adjusting screw is used to set the dcpth to which the needle can be shot beyond the tip of the probe. The depth and direction of the puncture can be determined aiming with two puncture guide lines on the ułtrasound monitor (Fig. 1.82). The total length of the instrument is about 80 cm.

The punctures are performed after the yestibulum and vagina are prepared asepticalły and the marę is se-dated. For the sake of sterility the instrumentation is covered in a stenie plastic sleeve. The tubę of the instrument with the attached punctuńng device is intro-duced into the vagina in the same manner as a tubular speculum. It is pushed against the anterior vaginal wali and one hand introduced into the rectum to hołd the uterus caudally and fix it against the ułtrasound probe. Once the image of the conceptus is aligned with the puncture direction of the needle the trigger mechanism is activated. The plastic sleeve is penetrated by the puncture needle when the trigger is pulied. It is possible to aspirate fetal fluid through the needle.