Tubal Pregnancy and Ectopic hCG Levels
Human Chorionic Gonadotropin in Pregnancy
Human chorionic gonadotropin (hCG) is produced by an embryo once implantation has occurred. In a healthy pregnancy, the embryo implants in the uterus and the developing placenta causes hCG levels to rise. One to two weeks after conception (3-4 weeks of pregnancy, as dated from the last menstrual period), the hCG levels will be high enough to trigger a positive result on a home pregnancy test. In early pregnancy, the hCG levels will double every 48-72 hours.
hCG levels can be monitored through a blood test. Quantitative beta hCG levels are determined every 48 hours to monitor pregnancies that are considered high risk. If the levels do not increase at the expected rate, the pregnancy is considered threatened. Slow rising hCG levels may indicate a non-viable intrauterine pregnancy, or may indicate an ectopic pregnancy has occurred.
What is an Ectopic Pregnancy?
When an egg is fertilized and implants in any location other than the uterus, the pregnancy is considered ectopic. The vast majority of ectopic pregnancies are found in a Fallopian tube. Other times, a pregnancy may implant in the abdomen, in an ovary, or on the cervix – these cases are much rarer than a tubal pregnancy.
When a pregnancy implants in a location outside the womb, the placenta cannot form normally and the hCG levels will not rise appropriately. In addition, spotting, cramping, and abdominal pain are often noted by the pregnant mother. If the pregnancy is far enough along, the ectopic pregnancy may be seen via transvaginal ultrasound.
Do you want to know how quickly your hCG levels are increasing? Try this hCG calculator:
This calculator will determine your doubling time and compare it to the average.
Slow Rising hCG Levels
In some healthy pregnancies, the beta hCG level does not double every 48 hours. Up to 15% of healthy pregnancies may experience a slow increase in hormone levels (less than 66% every 2 days). hCG levels that do not increase appropriately do result in a failed pregnancy 85% of the time, however, so close monitoring of the pregnancy is required.
In addition, once hCG levels reach 6,000, the rate of increase begins to slow in all pregnancies. Late in the first trimester, hormone levels begin to plateau – the hCG level may even decrease a bit in the early part of the second trimester to a new, stable level that will be maintained until the pregnancy is complete.
A single quantitative hormone level is not useful for the diagnosis of an ectopic pregnancy. Serial measurements must be taken over time to determine how likely a pregnancy is to proceed.
Quantitative beta hCG levels are not diagnostic for an ectopic pregnancy. These levels are simply part of a larger clinical picture – the diagnosis of an ectopic pregnancy includes the evaluation of hCG levels in addition to ultrasonography and a physical exam. If the pregnancy can be visualized in a Fallopian tube (or elsewhere), the ectopic is confirmed. If the pregnancy cannot be visualized at all, the pregnancy might be ectopic, depending on the hCG levels. If the hCG levels are above 1,800 and the embryo cannot be visualized in the womb, the suspicion for an ectopic pregnancy increases dramatically.
Normal vs. Slow Rising hCG
Ultrasound Diagnosis of Ectopic Pregnancy
Tubal Pregnancy Diagnosis
Many women suspect a problem early in pregnancy, as spotting and cramping or abdominal pain are often present. In some tubal pregnancies, there are no early warning signs, and the first sign of trouble may be a ruptured Fallopian tube.
If spotting and cramping are observed, a woman should call her physician immediately. A workup will generally be ordered, including beta hCG levels and ultrasound examinations to determine the location and viability of the pregnancy. If the hormone levels are rising less than 66% over a 48 hour period, an ectopic pregnancy will be suspected.
If the hCG levels are low (less than 1,800), the pregnancy may not be visible on the ultrasound machine. In this case, a woman is often presented with a choice to wait and monitor the pregnancy until it can be observed, or to have a procedure called a Dilation and Curettage (D&C) to determine if there is any pregnancy tissue is in the womb. If there is no tissue in the womb, the pregnancy is determined to be ectopic. This method of determining the location of the failing pregnancy is not preferred, as there is a chance that there is an intrauterine pregnancy, and a D&C will end the pregnancy. If this method is used, and a pregnancy is not found in the womb, the ectopic pregnancy may be treated with methotrexate. Methotrexate is injected and is often successful at ending an ectopic pregnancy without surgery.
If the hormone levels are over 1,800 and the pregnancy can be visualized in a Fallopian tube, the diagnosis is certain and treatment will be scheduled immediately (by methotrexate injection if the pregnancy is in a very early stage, or by removal of the pregnancy and Fallopian tube).
Symptoms of an Ectopic Pregnancy
Treatment with Methotrexate
If a tubal pregnancy is an early stage, the ectopic may be treated medically (as opposed to surgically). Methotrexate is successful at treating tubal pregnancies when:
- beta hCG levels of 5,000 or less.
- No cardiac activity of the embryo is observed.
- The Fallopian tube is not ruptured or torn.
Methotrexate works by preventing cell division and growth. The embryo breaks down and is passed from the Fallopian tube.
If Methotrexate is the chosen treatment option, hCG levels will be monitored on a regular basis until they have returned to 0. More than one injection of methotrexate is often required to successfully end a tubal pregnancy. If the hormone levels begin to drop after the treatment is started, blood tests will be performed weekly until the hCG cannot be detected. This may take anywhere from 1-3 months to occur. If the hormone levels fail to decrease after several rounds of methotrexate, surgical intervention is required.
Surgical Treatment for Ectopic Pregnancies
If medical treatment for an ectopic pregnancy fails, or if the tube ruptures or tears, surgical treatment will be required.
Ectopic pregnancies are the leading cause of first trimester deaths in pregnant women - a ruptured ectopic pregnancy is a medical emergency and must be treated immediately to save the mother's life. An ultrasound examination will generally show a significant amount of "free fluid" in the abdomen, indicating internal bleeding due to the ruptured Fallopian tube. A salpingectomy (removal of the Fallopian tube) is generally performed to remove the pregnancy and to stop internal bleeding. In some cases, the pregnancy is removed without the removal of the entire Fallopian tube - this procedure is called a salpingostomy.
Both types of surgery may be performed through tiny incisions (laparascopic surgery), though they may sometimes require a larger incision (laparotomy).
hCG levels may be monitored by a physician until the hormone level falls to undetectable levels.
Fertility after Ectopic Pregnancy
If a Fallopian tube is removed via salpingectomy and the other tube is healthy, many women will be able to conceive again.
If, however, the other tube is also affected by scar tissue or other abnormalities, fertility will be significantly impacted. Fertility treatments such as in-vitro fertilization (IVF) may be required to conceive in this scenario.
After a woman has experienced a tubal pregnancy, however, she is at an increased risk for having another ectopic pregnancy. Approximately 10-15% of women with a prior ectopic pregnancy will experience another ectopic. For this reason, all future pregnancies must be monitored with beta hCG levels and early utlrasound examinations may be performed to verify the location of the embryo.
The Author's Experience with a Tubal Pregnancy
I was approximately 5 weeks pregnant and had frequent spotting, so beta hCG levels were ordered by my obstetrician. My first result showed a level of 1,411. Two days later, a repeat blood draw indicated the level had only risen to 1,629. Three days later (over a weekend), the levels rose to 2,100. While the levels were increasing, they were rising so slowly that the pregnancy was considered a failure. I was offered a D&C, but refused since we couldn't visualize the pregnancy via ultrasound. A few days later, I woke to severe pain and rushed to the emergency room - the pregnancy was ectopic and had ruptured. I was bleeding internally and my blood pressure was dropping. I had emergency surgery to remove the Fallopian tube and pregnancy. The physical recovery took approximately one week, and I was told my other tube was not scarred, which improves our chances for conceiving again.