The use of ultrasound in pregnancy.

An ultrasound scan is a medical imaging diagnostic test used in obstetrics for over 20 years. With technological improvements, increased image quality and Doppler techniques, the capabilities and limitations can now be more clearly defined and cost effectiveness taken into consideration. This article reviews just what information a scan can provide and what it can't. The indications are divided into three main time periods. The 18-20 week scan which provides the most information and in many patients will be the only scan required. Reasons for performing the early pre 12 week and late post 26 week scans are also reviewed. Obstetric scanning has added significantly to the development of fetal medicine. This involves the antenatal detection of a condition, that may require treatment or alter management of the pregnant patient.

Synovial sarcoma: an unexpected ultrasound finding in a post-partum patient.

A 20-year-old patient presented after an uneventful pregnancy and delivery with an asymptomatic soft-tissue mass behind her knee with the clinical features of a ganglion or Baker's cyst. An ultrasound scan demonstrated a well-defined but solid mass with prominent vascularity. The mass was noted to increase in size prior to surgery. The pathological diagnosis was that of a synovial sarcoma grade 2, a rare malignant mesenchymal neoplasm with a serious prognosis.

Acardiac twins.

Three cases of twin pregnancy complicated by an acardiac twin are reported. This is a rare abnormality of twins. A vascular communication exists between the twins and the usually normal twin or so called 'pump' twin may develop cardiac failure as a result of perfusion of the abnormal twin. The acardiac twin is, generally, grossly abnormal with reduction anomalies, particularly of the upper part of the body, and gross oedema. Unless this abnormality is recognized the misdiagnosis of fetal death in utero may be made and the complications of the 'pump' twin may not be predicted. Three cases are presented with only one survivor.

Computed tomography pelvimetry: accuracy and radiation dose compared with conventional pelvimetry.

Several publications in the past few years have indicated that computed tomography (CT) pelvimetry is preferable to conventional pelvimetry when considering accuracy and radiation dose. Many of the previous publications have, however, compared state of the art CT pelvimetry with outmoded conventional pelvimetry techniques. This study compared both the accuracy and the radiation dose of CT pelvimetry with conventional pelvimetry as practised in two large teaching obstetric hospitals in Melbourne. The study did not demonstrate any significant difference in the accuracy between the two methods. The radiation dose to the fetal gonads was also similar. The radiation dose using CT pelvimetry could be significantly lowered if the axial CT section through the ischial spines were excluded from the CT technique.

Effect on pregnancy on gallstone formation.

An ultrasound study was carried out to determine the incidence of gallstone formation during pregnancy. One hundred and thirty seven pregnant women attending antenatal clinics were studied; 70 women were primigravidas and 67 were 1 para or more. An ultrasound of the gallbladder was carried out at 20 weeks or less of gestation and a repeat of ultrasound examination was performed soon after delivery. Five women had gallstones diagnosed before pregnancy; 1 of these was a primigravida, the other 4 were para 1 or more. None of the women developed gallstones during pregnancy. This finding suggests that pregnancy is unlikely to be an important factor in gallstone formation.

Pulmonary interstitial emphysema requiring lobectomy. Complications of assisted ventilation.

An infant with hyaline membrane disease treated with intermittent positive pressure ventilation developed pulmonary interstitial emphysema localised to one lobe after collapse of the affected lobe. The development of tension and further symptoms necessitated lobectomy, after which the infant became totally asymptomatic. Microscopy of the resected lobe showed the unusual feature of giant cells lining the air-containing cysts. The presence of these multinucleate cells suggested the cysts may have represented greatly dilated lymphatic channels resulting from rupture of gases into the pulmonary lymphatics.

Radiological findings in newborn infants with urinary infection.

Selective suprapubic urine aspiration was performed in 905 of 12 942 consecutive live-born infants and showed the presence of infection in 64 (0-5%). A majority (84%) of the infected infants were males. Radiological abnormalities were detected in 35 (55%). Because of this high incidence of abnormalities, which when diagnosed might alter management, it is suggested that radiological investigations be performed in newborn infants with proven urinary infection.