DOI: 10.12890/2025_005868
Inadequate absorption of intramuscular anti-D immunoglobulin in a pregnant woman with a high body mass index
Authors
ivica.maric@ztm.si
Keywords
D antigen, alloimmunisation, anti-D immunoglobulin, intramuscular injection, obesityAbstract
Introduction: The D antigen is highly immunogenic, and alloanti-D antibodies in maternal blood may cause haemolytic disease of the foetus and newborn. Prophylactic administration of anti-D immunoglobulin (Ig) to D-negative pregnant women significantly reduces the risk of alloimmunisation. However, absorption after intramuscular (IM) injection may be impaired in obese women.
Case description: We report the case of a 27-year-old D-negative pregnant woman body mass index (BMI) 35 kg/m2 who received three IM injections of anti-D Ig during pregnancy and after caesarean section. Despite confirmed administration, her indirect antiglobulin tests (IATs) remained negative or only borderline positive. Investigations excluded weak/partial D variants, foetomaternal haemorrhage, chimerism, and other causes. Due to her high BMI, we hypothesised that the injections were administered into subcutaneous fat, resulting in minimal absorption. After intravenous administration of anti-D Ig, the IAT became strongly positive, confirming correct drug delivery.
Conclusion: This case highlights the importance of considering maternal BMI in the administration of anti-D Ig. In obese women, inadequate IM administration may compromise prophylaxis. Intravenous administration or the use of alternative injection sites should be considered.
References
- Kennedy MS, Delaney M, Scrape S. Perinatal issues in transfusion medicine. In: Fung MK, Grossman BJ, Hillyer CD, Westhoff CM. Technical manual, 18th ed. Bethesda: AABB, 2014. p. 561-570
- Brinc D, Lazarus AH. Mechanisms of anti-D action in the prevention of haemolytic disease of the newborn. ASH Education Book January 1, 2009 vol. 2009 no. 1 185-191.
- Pravilnik o transfuzijskih preiskavah in postopkih ob transfuziji (Low about blood transfusion investigations and procedures with transfusion). Uradni list RS, st. 9/2007, 2007 (The Official Gazette of the Republic of Slovenia, no. 9/2007, 2007).
- Rhophylac: Summary of Product Characteristics [Internet]; [cited 2025 Sep 15]. Available from: Health Professional Information Leaflet.
- Rhesonativ: Summary of Product Characteristics [Internet]; [cited 2025 Sep 15]. Available from: Rhesonativ 625 IU per ml solution for injection ENG SmPC_09001bee807a752b.pdf
- Chan VO, Colville J, Persaud T, Buckley O, Hamilton S, Torreggiani WC. Intramuscular injections into the buttocks: are they truly intramuscular? Eur J Radiol 2006;58:480-484. doi: 10.1016/j.ejrad.2006.01.008
- Zaybak A, Günes UY, Tamsel S, Khorshid L, Esser I. Does obesity prevent the needle from reaching muscle in intramuscular injections? J Adv Nurs 2007;58:552-556. doi: 10.1111/j.1365-2648.2007.04264.x
- Qureshi H, Massey E, Kirwan D, Davies T, Robson S, White J, et al. BCSH guideline for the use of anti-D immunoglobulin for the prevention of haemolytic disease of the fetus and newborn. Transfus Med 2014;24:8-20. doi: 10.1111/tme.12091
- Bichler J, Schöndorfer G, Pabst G, Andresen I. Pharmacokinetics of anti-D IgG in pregnant RhD-negative women. BJOG 2003;110:39-45
- MacKenzie IZ, Roseman F, Findlay J, Thompson K, Jackson E, Scott J, et al. The kinetics of routine antenatal prophylactic intramuscular injections of polyclonal anti-D immunoglobulin. BJOG 2006;113:97-101. doi: 10.1111/j.1471-0528.2005.00789.x
- Woelfer B, Schuchter K, Janisiw M, Hafner E, Philipp K, Panzer S. Postdelivery levels of anti-D IgG prophylaxis in D- mothers depend on maternal body weight. Transfusion 2004;44:512-517. doi: 10.1111/j.1537-2995.2004.03287.x
- Ngan CBM, Kaur R, Jackson DE. Does high body mass index (>25 kg/m2) or weight (>80 kg) reduce the effectiveness of anti-D prophylaxis in Rh(D)-negative pregnant women? A systematic review and meta-analysis. Vox Sang 2024;119:902-911. doi: 10.1111/vox.13693
- Expert Panel Consensus Position Statement regarding the Use of Rh(D) Immunoglobulin in Patients with a Body Mass Index > 30 [Internet]; [cited 2025 Sep 15]. Available from: Use of Rh(D) Immunoglobulin in Patients with High BMI (Australian Red Cross Blood Service and NBA Consensus Position Statement)
