Difficulties in Immunohaematology : The Weak D Antigen

Background

The Rh blood system is one of the most polymorphic and immunogenic systems known to humans. The expression of Rh blood group antigen is complex. The Rh D antigen is the most important of the antigens that constitute the Rh antigen system. In most cases, D antigen can easily be detected. However, due to variability of expression, weak forms antigen are encountered. The reactivity of weak D with antisera is variable and presents as a problem in blood banking.

Methods

A retrospective analysis for a five-year period was done. Blood samples that were negative for Rh D by immediate spin tube method were tested for weak D antigen by additional lab tests.

Result

Of 34932 serial Rh grouping tests done in our Blood Bank, the incidence of weak D Rh antigen was 0.189%. All these were confirmed by the antiglobulin test.

Conclusion

These patients present as a problem for the blood banker and a curiosity to the clinician. Although uncommon, all health care workers should be aware of this entity to avoid anti D alloimmunisation.Key Words: Weak D, Rh Blood Group     

The oral contraceptive pill effectively permits cycle batching for an intermittent in vitro fertilization programme in Trinidad and Tobago

Assisted reproductive technology (ART) in small island states like Trinidad and Tobago is usually provided in batches so as to minimize the cost of providing the service. As a result, patients 'cycles have to be synchronized in order to coincide with the arrival of a visiting embryologist. This is a retrospective study which evaluates the experience of pre-treatment with an oral contraceptive pill (OCP) as a means of batching cycles for an intermittent ART programme. Seventy-four in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycles in which OCP usage was employed (Group A), were compared with 121 cycles which did not require pharmaceutical manipulation (Group B). In both groups more than 50% of women were older than 36-years. Two cycles were cancelled in Group A and seven in Group B, because of poor ovarian response. Although the pregnancy rate per treatment cycle was higher in Group A than in Group B (26.3% vs 17.3%), this difference was not significant. More spontaneous miscarriages occurred in the non-OCP women and ovarian cyst formation was more common in these women. The authors experience indicates that the OCP is a simple, cheap and efficient means of batching patients for an intermittent ART programme and can be utilized in other small ART centres.     

Gauze packing for aspirin-induced hemorrhage in vaginal hysterectomy

Intra-abdominal packing has been used to control massive hemorrhage in many difficult situations. Gynecologists are finding it increasingly useful in controlling persistent hemorrhage in a variety of situations. Recently we found it necessary to use packing for persistent brisk bleeding during vaginal hysterectomy in a patient on aspirin therapy for heart disease. We could find no similar report in the literature and now describe our experience.Abbreviations INR International normalized ratio     

Intraoperative placement of a self-retaining Foley catheter for continuous drainage of malignant ascites

Malignant ascites in advanced cancer is usually treated by repeated paracentesis, causing both discomfort and inconvenience to patients in the terminal stages of disease. We present a case of advanced ovarian carcinoma in which intraoperative placement of a Foley's self-retaining catheter into the peritoneal cavity was used to facilitate long-term continuous drainage of malignant ascites. This is a simple, convenient and cost-effective method which decreases the need for repeated hospital admissions. The aim complication might be peritonitis, but with proper care of the device and the use of antibiotics, this was not seen in our patient.     

In vitro antagonistic activity of monoterpenes and their mixtures against 'toe nail fungus' pathogens

The antibiotic effect of the active ingredients in Meijer medicated chest rub (eucalyptus oil, camphor and menthol) as well as the inactive ingredients (thymol, oil of turpentine, oil of nutmeg and oil of cedar leaf) were studied in vitro using the fungal pathogens responsible for onychomycosis, such as the dermatophytes Tricophyton rubrum, Trichophyton mentagrophytes, Microsporum canis, Epidermophyton fl occosum and Epidermophyton stockdale. The zones of inhibition data revealed that camphor (1). menthol (2). thymol (3). and oil of Eucalyptus citriodora were the most efficacious components against the test organisms. The MIC(100) for mixtures of these four components in various carrier solvents revealed that formulations consisting of 5 mg/mL concentrations of each have a potential to be efffective in controlling onychomycosis.     

Use of continuous fluid drainage for severe polyhydramnios due to twin to twin transfusion syndrome

Acute polyhydramnios due to twin to twin transfusion is a rare complication of twin pregnancies which, despite treatment, has a high perinatal mortality. Repeated decompression amniocentesis has been used but is associated with certain risks. We report the use of continuous, gradual fluid drainage as an alternative method of uterine decompression.     

Initial experience with in-vitro fertilization technology in the English-speaking Caribbean

This audit documents the first experience with in-vitro Fertilization technology in the English-speaking Caribbean. From 1996 to 2000, 121 cycles have been performed in 99 couples utilizing these techniques. After ovarian stimulation, 1,103 oocytes were retrieved (average 9.1) and of these, 65% fertilized normally, with embryo transfer possible in 111 cycles. Twenty-one pregnancies were recorded (21.2% per patient and 18.9% per embryo transfer) and the live birth rate per patient was 12.1%. The trend was for the success rate to be better in patients under age 36 years.     

Effects of fibroblast growth factor-4 (k-FGF) on long-term cultures of human bone marrow cells

Fibroblast growth factor-4 (FGF-4), a highly mitogenic protein encoded by the k-fgf/hst oncogene, stimulates the growth of a variety of cells of mesenchymal and neuroectodermal origin. Addition of FGF-4 to human long-term bone marrow cultures increased both the cell density of the stromal layer and the number of hematopoietic colony forming cells in the cultures in a dose-dependent manner. Hematopoiesis in the stromal layer persisted for up to 8 months. Erythropoiesis was maintained for up to 4 weeks, but granulocytes were the predominant nonadherent cell type. Cultures treated with FGF had increased numbers of monocytes compared with control cultures and some CD14+, CD45+ monocytes could still be detected after 8 months of continuous culture. The addition of the growth factor increased the rate of growth of the stromal layer and appeared to delay its senescence. Subcultures made in the presence of FGF-4 had up to 10-fold increases in plating efficiency and grew as relatively uniform monolayers. These subcultures retained the capacity to support hematopoiesis for several months, while untreated subcultures, made without FGF-4, grew erratically and generally lost the capacity to support hematopoiesis within 4 to 6 weeks. The improved growth after subculture greatly enhanced the reliability of limit- dilution assays of multipotential hematopoietic stem cells that use stromal cell monolayers. The primary effect of FGF-4 appeared to be on the stromal cells of the long-term bone marrow cultures, but a direct effect on hematopoietic progenitors could not be ruled out.