Written by Dr.M.D.Mazumdar, MD
Implantation bleeding is a common cause of bleeding in early pregnancy . It occurs at the time of implantation of the fertilized ovum. The bleeding is seen about 10-14 after conception which is roughly at around the same day as the next due periods.
The bleeding is usually not accompanied by any pain or discomfort. It lasts for only about 2-3 days and decreases spontaneously.
The problem with implantation bleeding is that many women confuse this with a normal period.
Only about 10% of all pregnant women experience implantation bleeding.
Cause of Implantation Bleeding
At about 6 - 10 days after fertilization of the ovum, the fertilized egg (called the 'zygote') reaches the inner cavity of the uterus (see 'How Pregnancy Occurs'). And 2-3 days later ( on the 9-12th day from fertilization), it proceeds to attach itself to the inner lining of the uterus ('endometrium').
The zygote is surrounded by a highly specialized tissue called the trophoblast. This trophoblast has the capacity of being able to burrow into the endometrium. The process of burrowing into the endometrium is called 'implantation'.
During implantation, the trophoblast with the egg imbedded in it continues to burrow deep into the uterine endometrium until it is completely enclosed by it. During this process, some of the mother's blood vessels are opened up, diverting some blood into cavities inside the trophoblast. If the cavities (called 'blood lakes') are near the surface of the endometrium, some of the blood may leak out into the uterine cavity.
This blood trickles out of the uterus to the vagina and mixes with normal vaginal discharge. This may be seen as pink or brown stained vaginal discharge - the colour of blood changes to brown if bleeding had occured a few days earlier and the blood undergoes denaturation.
The bleeding is normally so slight that it is not noticed or ignored by most women. Many women confuse this implantation bleeding for a normal period. On some occasions however it may be heavy enough to cause the woman to panic and consult the doctor.
The urine test for pregnancy may show a positive result 2-3 days after the implantation bleeding, when the level of the HCG hormone starts to rise in the blood. But it is better to do the test 7 days after the missed period for an accurate result.
Diagnosis of Implantation Bleeding
Implantation bleeding has some definite characteristics:
- Time: Implantation bleeding occurs about 10 to 14 days after ovulation or just about the time of the next menstrual period.
- Amount of bleeding: The bleeding is usually very slight- sometimes the normal vaginal discharge may just be tinged pinkish or brownish. Occasionally however it may be more but in all cases it is far less than the normal menstrual blood flow.
- Pain: Implantation bleeding is usually not accompanied by pain or cramping. Sometimes, mild cramping may occur due to congestion of the uterus in early pregnancy. Bleeding which occurs a few days after a missed period and is accompanied by cramping may be a symptom of an impending abortion.
- Cycle of Flow: Implantation bleeding fades away spontaneously. Sometimes it may have the typical flow cycle of 'less flow-high flow-decreasing flow-no flow'. But the bleeding is always far less than a normal menstrual period.
Treatment of Implantation Bleeding:
As implantation bleeding is a normal occurance and clears up by itself, there is no specific treatment.
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