By Dr. Dusan, MD
Placenta accreta is a serious pregnancy condition that occurs when the placenta grows too deeply into the wall of the uterus. Normally, after childbirth, the placenta detaches from the uterine wall. However, in the placenta accreta, either all or part of the placenta remains attached to the uterine wall. This can lead to severe bleeding after delivery. Because of this, placenta accreta is considered a very serious medical condition. As this condition is usually diagnosed during pregnancy, delivery usually ends by an early C-section followed by surgical removal of the uterus (hysterectomy).1
A significant risk factor for placenta accreta is placenta previa (“low lying placenta”) along with the presence of a uterine scar. Because of that, every woman with a placenta previa should undergo regular follow-up with ultrasound with special attention to placenta accreta.2
Prior Cesarean delivery, uterine instrumentation, and intrauterine scarring, as well as placenta previa, smoking, maternal age over 35, grand multiparity, and recurrent miscarriage, are all risk factors for placenta accreta. Diagnosis of the placenta accreta is usually made by ultrasound in the second or third trimester.2
In the last decade, the incidence of this pregnancy condition has risen from 0.8 to 3 per 1000 deliveries. If a woman has a cesarian section during her life, this increases the chance to 5% to have placenta accreta, compared to women that have not had C-section in their life.3
Generally, there are two approaches to treat placenta accreta, surgical and non-surgical and which approach is the best depends on the severity of the condition. As mentioned above, bleeding is a significant and serious complication that can occur not only due to the condition itself per se but also as a complication during surgery.3
As there is a bunch of collateral blood vessels, blood oozing is quite common. In order to prevent this blood oozing and more serious, life treating bleeding, aortic cross-clamping can be done. Simply speaking, one of the largest blood vessels in the abdomen is squeezed and, in this way, the blood supply to the uterus is reduced, preventing bleeding in this way.3
Although some research showed that this can prevent severe bleeding, there is a number of potential complications related to this surgical method. The main one is ischemia of all organs distally from the place of clamping. As the cross-clamping last longer, the chance for this complication significantly increases.3,4
In addition to the distal organ ischemia, abdominal aorta cross-clamping can lead to heart failure and increased oxygen demands of the heart muscle caused by the alteration of blood volume due to clamping. Because of these potential complications of abdominal aorta cross-clamping, it is very important to improve microcirculation after cross-clamping has been done. To improve microcirculation transdermal CO2 can be applied. Increased CO2 will lead to increased O2 release from hemoglobin into the tissues.3,4
CO2 has a vasodilatory effect (widen blood vessels) and in that way increase blood flow. This effect is based on the affinity of O2 and CO2 towards hemoglobin increased CO2 leads to the increased percentage of molecules of oxygen to be released from hemoglobin. This is based on the principles of Bohr and Haldane effects. In this way, tissue oxygenation of local microcirculation can be improved after abdominal cross-clamping.3
The study that was done by G. Damanik at. examined the effects of CO2 on microcirculation in pregnant women with placenta accreta who underwent temporary abdominal aorta cross-clamping followed by hysterectomy. As mentioned above, massive collateral circulation in placenta accreta can be found. This is particularly visible in the posterior bladder and pelvic ligaments, so ligation of blood vessels due to this is needed.3
As this collateral circulation might be the source of serious blood oozing during a surgical procedure on the uterus, the researchers clamped the abdominal aorta at the infrarenal level to stop the bleeding. However, although the chance of severe bleeding was drastically reduced, clamping the abdominal aorta generates temporary ischemia in lower limbs, creating anaerobic metabolism followed by increased lactate levels. Due to this complication, researchers applied transdermal CO2 in order to improve tissue oxygenation and prevent or reduce potential ischemia.3,4
The research suggests that transdermal applied CO2 increases the partial pressure of oxygen in the capillaries 25-45 mmHg and increases as well deoxygenated hemoglobin 10-20 mg/dL. This increase in deoxyhemoglobin (a form of hemoglobin that occur after the molecules of oxygen are released from hemoglobin) occurs as the consequence of the increased releasing of oxygen to the tissue and capillary network.3
Data from another research confirmed that the application of transdermal CO2 increases tissue perfusion. In addition, the increase in partial pressure of O2 causes a vasomotor effect (a dilatation of capillaries) leading to improved perfusion (blood supply) of the tissues.3
There is an apparent reduction in operative blood loss after the use of temporary abdominal aorta cross-clamping of the infrarenal abdominal aorta during cesarean hysterectomy and improved tissue perfusion after transdermal CO2 has been applied.3,4
- Belfort, M. A., Publications Committee, & Society for Maternal-Fetal Medicine. (2010). Placenta accreta. American journal of obstetrics and gynecology, 203(5), 430-439.
- Esakoff, T. F., Sparks, T. N., Kaimal, A. J., Kim, L. H., Feldstein, V. A., Goldstein, R. B., … & Caughey, A. B. (2011). Diagnosis and morbidity of placenta accreta. Ultrasound in Obstetrics & Gynecology, 37(3), 324-327.
- Damanik, G., ItoPuruhito, R. A. A., Lestari, P., Soebroto, H., & Revianto, O. (2021). Transdermal CO2 Increases Perfusion Index in Patients with Placenta Accreta Following Temporary Abdominal Aortic Cross-Clamping. Annals of the Romanian Society for Cell Biology, 25(6), 19918-19923
- Chou, M. M., Chen, M. J., Su, H. W., Chan, C. W., Kung, H. F., Tseng, J. J., … & Yuan, J. C. (2021). Vascular control by infrarenal aortic cross‐clamping in placenta accreta spectrum disorders: description of technique. BJOG: An International Journal of Obstetrics & Gynaecology, 128(6), 1030-1034.