Ultrasound and color Doppler imaging revealed:
Can this be RPOC or retained products of conception with urine pregtest negative?
Yes, it is possible for a urine pregnancy test to remain negative in retained products of conception (RPOC) 4 months after an abortion. This is because the level of human chorionic gonadotropin (hCG) in the blood may not be high enough to be detected by a urine pregnancy test. hCG is a hormone produced by the placenta during pregnancy, and it is usually undetectable in the blood 2-3 weeks after a miscarriage or abortion. However, in some cases, the level of hCG may remain elevated for longer, even in the absence of a pregnancy. This is what is known as a "blighted ovum" or an "anembryonic pregnancy."
In cases of RPOC, the retained tissue may continue to produce hCG, even though it is no longer viable. This can lead to a false-negative urine pregnancy test, even if the woman is not actually pregnant.
Here are some additional things to keep in mind:
* The sensitivity of urine pregnancy tests varies, so it is possible that a negative test could be a false negative.
One of the closest differential diagnoses for RPOC is AVM:
How to differentiate between RPOC and AVM of uterus?
Some points on how to differentiate between RPOC in uterus and uterine AVM on ultrasound and color Doppler imaging:
* RPOC:
* On ultrasound, RPOC may appear as a heterogeneous mass in the uterus, usually within the uterine cavity.
* On color Doppler imaging, RPOC may show areas of vascularity, but the vascularity is typically less pronounced than in AVM.
* The peak systolic velocity (PSV) in RPOC is typically less than 100 cm/s.
* Uterine AVM:
* On ultrasound, uterine AVM may appear as a hypervascular mass in the uterus.
* On color Doppler imaging, uterine AVM shows a characteristic "mosaic" pattern of vascularity, with areas of high-velocity flow and areas of low-velocity flow.
* The PSV in uterine AVM is typically high, often greater than 100 cm/s.
In addition to the above, there are some other factors that can help to differentiate between RPOC and AVM, such as:
* The patient's history: RPOC is more likely to occur in women who have had a recent miscarriage or abortion, while AVM is a rare condition that can occur in women of any age.
* The patient's symptoms: RPOC is more likely to cause symptoms such as vaginal bleeding, abdominal pain, and fever, while AVM may be asymptomatic or cause only mild symptoms.
* The results of other tests: A blood test to measure hCG levels may be helpful in differentiating between RPOC and AVM. In RPOC, the hCG levels will typically be elevated, while in AVM, the hCG levels will be normal.
Finally we arrive at a diagnosis of: RPOC in this case.
MRI scan in uterine AVM can confirm the diagnosis of RPOC and rule out AVM:
MRI findings of AVM:
*Uterine enlargement: The uterus may be enlarged due to the presence of the AVM.
* Interruption of the uterine junctional zone: The uterine junctional zone is the area between the endometrium and the myometrium. It is normally seen as a thin, dark line on MRI scans. In patients with uterine AVM, the junctional zone may be interrupted or absent.
* Enlarged myometrial and parametrial vessels:
The myometrium is the muscular layer of the uterus. The parametrium is the tissue that surrounds the uterus. In patients with uterine AVM, the myometrium and parametrium may be enlarged due to the presence of the AVM.
*Flow voids: Flow voids are areas on MRI scans that appear dark because there is no blood flowing through them. In patients with uterine AVM, flow voids may be seen in the myometrium and parametrium. These flow voids represent the dilated blood vessels that are characteristic of AVMs.
* Dynamic MR angiography: Dynamic MR angiography is a type of MRI scan that allows doctors to see how the blood flows through the AVM. This information can be helpful in determining the best treatment options for the patient.
Overall, MRI scans can be a valuable tool in the diagnosis of uterine AVM.
Images in this case are courtesy of Dr Golam.
For more on this topic visit Sonography of uterus
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