1993-07-07-13 Twin, acardiac, cephalic © Bala www.thefetus.net/
Twin, acardiac, cephalic
Kanu G. Bala, MBBS, FCGP*, Kohinoor Begum, MBBS, FCPS
* Address correspondence to Kanu G. Bala, MBBS, FCGP Mina Laboratory, 98 New Elephant Road, Dhaka 1205, Bangladesh. Ph: 011-880-2-502-298
Companion case report
The following is submitted as a companion case to the previous and following cases because it demonstrates an interesting variance on the same subject (see Discussion).
A 25-year-old primigravida was first seen at 7 weeks of amenorrhea. On physical examination the uterus was non-palpable. At 12 weeks the uterus was found enlarged on physical examination— corresponding to a 16-week size. The patient was referred for ultrasound to exclude a twin pregnancy. On ultrasound, discordant- sized twins were found with BPD of 25 mm for the large twin and 16 mm for the other twin. No fetal heart movement was detected for the smaller twin, which was therefore considered to be dead. Aside from the presumed fetal demise, the smaller twin was apparently normal anatomically within the limits of the resolution of the ultrasound equipment used. The amniotic fluid was normal and there was no evidence of membrane between the gestational sac. The patient returned at 21 weeks and, on examination, the larger twin had increased appropriately (the BPD was now 57 mm) but surprisingly the presumed dead fetus had increased its BPD size from 16 to 38 mm. This was inappropriate growth for a live twin but was nevertheless remarkable. Again, on the second examination, no heartbeat was obtained. On the basis of the growth of the twin without cardiac activity, the diagnosis of twin reverse arterial perfusion syndrome was made. At 29 weeks the patient went into premature labor and delivered two dead fetuses.
Figure 1: First examination at 16 weeks. The smaller fetus (FB) does not present evidence of cardiac activity and is thus suspected to be dead.
Figure 2: At 21 weeks, however, both biparietals have increased, and in the absence of cardiac activity of the smaller twin, the diagnosis of acardiac, cephalic twin is made.
Fig 3: Growth of the biparietal diameters
This case is interesting for two reasons. First, this is a unique form of acardiac twin: it is extremely rare to have a cranial formation sufficient as to appear at least superficially normal. The second point of interest is more philosophical. For all of us, bleeding edge of technology fans, it illustrates that a difficult and rare diagnosis can be arrived at in spite of a resolution that few of us would be willing to live with.
A common complaint that I hear when I travel abroad is that, in less fortunate nations than the USA, physicians are handicapped by a slow turnover of equipment and the difficulty in having access to modern technology. Our department, for instance, has more color Doppler units than a whole country that I recently visited. None of us would certainly give up our equipment, but Drs. Bala and Begum deserve our admiration for reminding us that clever thinking can get a long way towards palliating the deficiencies or absence of state of the art equipment.