Ventricular tap under direct ultrasound control.

The time of administration has varied from 24 hours to 5 weeks before delivery,2 and in most cases exchange transfusion or phototherapy, or both, was required to control the jaundice. In 2 cases respiratory distress was reported as well3 4 although it is difficult to determine whether or not this was related to the dye. In this case the L/S ratio at the time of amniocentesis was 2-4. Although methylene blue was not looked for in the baby's urine, the high reticulocyte count of 16% is clear evidence of active haemolysis, and in the absence of blood group incompatibility, infection, or red cell enzyme defect it was felt that methylene blue was strongly implicated as the cause of the haemolysis in this patient. In addition, the amount of methylene blue administered was large (about 70 mg), being greater than the dose used in other reported cases2-4 and far exceeding the dose of 1 -6 mg suggested by Plunkett2 as insufficient to cause haemolysis. A recent report5 of inadvertent intrauterine injection of methylene blue at 5j weeks' gestation, followed by a normal delivery at term with no ensuing haematological problems, suggests that the dye does not necessarily affect the embryo and that its use for 'diagnosis of premature rupture of membranes should not be condemned'. It may be that the length of time between dye administration and delivery is relevant with respect to the development of haematological problems, but since this length of time cannot be predicted and problems have been reported up to 5 weeks after administration of dye, this procedure may be potentially harmful at any gestation. Methylene blue is not an innocuous drug and its use for detection of premature rupture of the membranes should be avoided.