Abortion (miscarriage)- Basics & Causes

Abortion (miscarriage)- Basics & Causes

Q. 1

A lady has recurrent abortions in 1st trimester with a history of the autosomal recessive disorder in the family. The true statement regarding this is:

 A Consanguinity may be the cause

 B Complete penetrance is common

 C

Affected members in the family

 D

All are correct

Q. 1

A lady has recurrent abortions in 1st trimester with a history of the autosomal recessive disorder in the family. The true statement regarding this is:

 A

Consanguinity may be the cause

 B

Complete penetrance is common

 C

Affected members in the family

 D

All are correct

Ans. D

Explanation:

Ans. is D. i.e. All are correct

Characteristics of autosomal recessive disorders

Autosomal recessive inheritance is the single largest category of Mendelian disorders.

They have the following features :

  • The trait does not usually affect the parents but siblings may show the disease (Option “c” is correct).
  • Siblings have one chance in four of being affected (i.e. recurrence risk is 25% for each birth).
  • Consanguinity may be the cause (option a is correct).
  • The expression of the defect tends to be more uniform than in autosomal dominant disorders.
  • Complete penetrance is common (Option b is correct).
  • Onset is frequently early in life.

In the question the lady has recurrent abortions and H/o autosomal recessive disorder in the family, therefore all features of autosomal recessive disorders apply to her


Q. 2 Spontaneous abortion in 1st trimester is caused by:

 A Trisomy 21

 B

Monosomy

 C

Trauma

 D

All

Ans. D

Explanation:

Ans. is D. i.e All (Trisomy 21; Monosomy; and Trauma)

COMMON CAUSES OF MISCARRIAGE:

First trimester:

Genetic factors (50%)

Endocrine disorders (LPD, thyroid abnormalities, diabetes)

Immunological disorders (autoimmune and alloimmune)

Infection:

  – Viral: Rubella, Cytomegalovirus, Variola, Vaccinia or HIV.

  – Parasitic: Toxoplasma, Malaria

– Bacteria: Ureaplasma, Chlamydia,Syphilis ,Brucella.

Unexplained

* Trauma

Second trimester: 

Anatomic abnormalities

Cervical incompetence (congenital or acquired)

Müllerian fusion defects (bicornuate uterus, septate uterus)

Uterine synechiae.

Uterine fibroid

Maternal medical illness

Unexplained


Q. 3 Most Common cause of abortion in the first trimester is a defect in:

 A

Placenta

 B

Uterus

 C

Embryo

 D

Ovarian

Ans. C

Explanation:

Ans. C i.e. Embryo

  • The most common cause of abortion in the first trimester is chromosomal abnormalities involving the zygote or embryo.
  • Approximately half of the miscarriages are anembryonic, that is, with no identifiable embryonic elements. Less accurately, the term blighted ovum may be used.
  • The other 50 % are embryonic miscarriages, which commonly display a developmental abnormality of the zygote, embryo, fetus, or at times, the placenta.
  • Of embryonic miscarriage, half of these—25 percent of all abortuses—have chromosomal anomalies and thus are aneuploid abortions.
  • The remaining cases are euploid abortions, that is, carrying a normal chromosomal complement.

Q. 4 Commonest chromosomal anomaly leading to spontaneous abortions is :

 A

Trisomy 16

 B

Trisomy 21

 C

Tetraploidy

 D

Turner’s syndrome

Ans. A

Explanation:

Trisomy 16

  • Trisomy 16 is the most common trisomy found with first-trimester losses, accounting for 18.3 percent, but it is not identified later in gestation.

Q. 5  Causes of 1st-trimester abortion are all except :

 A

Rubella

 B

Syphilis

 C

Defective Germplasm

 D

None

Ans. D

Explanation:

Ans. is D. i.e. None

COMMON CAUSES OF MISCARRIAGE:

First trimester:

Genetic factors (50%)

Endocrine disorders (LPD, thyroid abnormalities, diabetes)

Immunological disorders (autoimmune and alloimmune)

Infection:

  – Viral: Rubella, Cytomegalovirus, Variola, Vaccinia or HIV.

  – Parasitic: Toxoplasma, Malaria

Bacteria: Ureaplasma, Chlamydia,Syphilis ,Brucella.

Unexplained.

Second trimester: 

Anatomic abnormalities

Cervical incompetence (congenital or acquired)

Müllerian fusion defects (bicornuate uterus, septate uterus)

Uterine synechiae.

Uterine fibroid

Maternal medical illness

Unexplained


Q. 6

Abortions in the second trimester are mostly due to:

 A

Incompetent cervix

 B

Defective genes

 C

Tuberculosis

 D

Trauma

Ans. A

Explanation:

Ans. is A. i.e. Incompetent cervix

Some Causes of Midtrimester Spontaneous

  • Fetal anomalies
    • Chromosomal
    • Structural
  • Uterine defects
    • Congenital
    • Leiomyomas
    • Incompetent cervix
  • Placental causes
    • Abruption, Previa
    • Defective spiral artery transformation
    • Chorioamnionitis
  • Maternal disorders
    • Autoimmune
    • Infections
    • Metabolic

Q. 7 The most common cause of Abortion :

 A

Ovo Fetal factor

 B

Maternal hypoxia

 C

Uterine fibroid

 D

Cervical incompetence

Ans. A

Explanation:

Ans. is A. i.e. Ovo Fetal factor

  • Approximately half of the miscarriages are anembryonic, that is, with no identifiable embryonic elements. Less accurately, the term blighted ovum may be used.
  • The other 50 percent are embryonic miscarriages, which commonly display a developmental abnormality of the zygote, embryo, fetus, or at times, the placenta.

Q. 8 An internationally accepted definition of abortion is the expulsion of the products of conception :

 A

Before 28th week of gestation or 1 kg (weight of fetus)

 B

Before 24th week of gestation or 750 gms (weight of fetus)

 C

Before 20th week of gestation or 750 gms (weight of fetus)

 D

Before 20th week of gestation or 500 gms (weight of fetus)

Ans. D

Explanation:

Ans. is D. i.e. Before 20th week of gestation or 500 gms (weight of fetus)

  • National Center for Health Statistics, the Centers for Disease Control and Prevention, and the World Health Organization all define abortion as pregnancy termination before 20 weeks’ gestation or with a fetus born weighing < 500 g.
  • These criteria, however, are somewhat contradictory because the mean birth weight of a 20-week fetus is 320 g, whereas 500 g is the mean for 22 to 23 weeks

Q. 9 The commonest chromosomal abnormality in early spontaneous abortions is :

 A

Monosomy

 B

Autosomal trisomy

 C

Triploidy

 D

Tetraploidy

Ans. B

Explanation:

Autosomal trisomy

  • With first-trimester miscarriages, autosomal trisomy is the most frequently identified chromosomal anomaly.
  • Although most trisomies result from isolated nondisjunction, balanced structural chromosomal rearrangements are found in one partner in 2 to 4 percent of couples with recurrent miscarriages.
  • Trisomies have been identified in abortuses for all except chromosome number 1, and those with 13, 15, 16, 18, 21, and 22 are most common.
  • Single autosomal trisomies represent the largest class of chromosome abnormalities in spontaneous miscarriages. 
  • Trisomy 16 is the most frequent one (18.7% of the single autosomal trisomies), followed by trisomy 22 (18.5%), trisomy 15 (14.2%), and trisomy 21 (12.2%)

Q. 10 Spontaneous abortions commonly occur during-

 A

First week

 B

Second trimester

 C

Third trimester

 D

Before 16 weeks

Ans. D

Explanation:

Ans. D. Before 16 weeks

  • Abortion is the expulsion or extraction from its mother of an embryo or fetus weighing 500 g or less when it is not capable of independent survival (WHO).
  • This 500 g of fetal development is attained approximately at 22 weeks (154 days) of gestation.
  • The expelled embryo or fetus is called an abortus. The word miscarriage is the recommended terminology for spontaneous abortion.
  • More than 80 percent of spontaneous abortions occur within the first 12 weeks of gestation.

Q. 11 Abortion is the expulsion or extraction from the uterus, spontaneous or induced, or the fetus or embryo weighing:

 A

Less than 100 gm

 B

Less than 50 gm

 C

Less than 250 gm

 D

Less than 500 gm

Ans. D

Explanation:

Ans. is D. i.e. Less than 500 gm

  • Abortion is the expulsion or extraction from its mother of an embryo or fetus at less than 20 weeks, or weighing 500 g or less when it is not capable of independent survival.
  • Period of viability depends on the medical facilities of a country and hence varies.
  • As per WHO-22 weeks.
  • As per ACOG-24 weeks.
  • In India: beyond 28 weeks, Fetus is l00% viable.

Weight of fetus

  • At 20 weeks, the weight of fetus-300 gm
  • Between 22-23 weeks-500 gm.
  • At 24 weeks, the weight of fetus-630 gms.
  • At 28 weeks, the weight of fetus-1 kg
  • 500 g of fetal development is attained approximately 22 weeks (154 days) of gestation.

Q. 12 Which is the most common uterine malformation seen in cases of recurrent abortions?

 A

Mullerian fusion defects

 B

Uterine syncytium

 C

Unicornuate uterus

 D

Uterine agenesis

Ans. A

Explanation:

Ans. is A. i.e. Mullerian fusion defects

  • Mullerian duct anomaly is an important cause of recurrent miscarriage in early and mid-trimester.
  • Septate or arcuate uterus is the most common uterine anomaly associated with Mullerian fusion defects and it is the most common defect associated with repeated pregnancy loss.
  • In septate uterus: both Mullerian duct fuse & form septa but septa fails to resolve. So the uterus is outwardly normal but contains a complete or incomplete septum inside.
  • In the arcuate uterus, the fundus of the uterus remains flat & does not become dome-shaped.
  • on HSG in the septate uterus, an angle of less than 75° between the uterine horns is suggestive of a septate uterus, and an angle of more than 105° is more consistent with bicornuate uteri.
  • Management for septate uterus:
  1. Earlier: Jones/Tompkins Metroplasty was done.
  2. Nowadays: Hysteroscopic resection of septa is being done after inducing endometrial atrophy by administering the GnRH analogue for 2 months.
  • Main complications: Uterus perforation and fluid overload.

Q. 13 The effects of diabetic mother on infants is/are:

 A

Brain enlargement as a part of macrosomia

 B

Hyperglycemia in infant

 C

First-trimester abortion

 D

All of the above

Ans. C

Explanation:

Ans. C. i.e. First-trimester abortion

COMMON CAUSES OF MISCARRIAGE:

First trimester:

Genetic factors (50%)

Endocrine disorders (LPD, thyroid abnormalities, diabetes)

Immunological disorders (autoimmune and alloimmune)

Infection:

  – Viral: Rubella, Cytomegalovirus, Variola, Vaccinia or HIV.

  – Parasitic: Toxoplasma, Malaria

-Bacteria: Ureaplasma, Chlamydia,Syphilis ,Brucella.

Unexplained.

Second trimester:

Anatomic abnormalities

Cervical incompetence (congenital or acquired)

Müllerian fusion defects (bicornuate uterus, septate uterus)

Uterine synechiae.

Uterine fibroid

Maternal medical illness

Unexplained


Q. 14

Abortion is defined as expulsion of the fetus: 

 A

Before viability

 B

Before 28 weeks

 C

Before full-term

 D

None of the above

Ans. A

Explanation:

Ans.A. Before viability

  • Abortion is the expulsion or extraction from its mother of an embryo or fetus at less than 20 weeks, or weighing 500 g or less when it is not capable of independent survival.
  • Periods of viability depends on the medical facilities of a country and hence varies.
  • As per WHO-22 weeks.
  • As per ACOG-24 weeks.
  • In India: beyond 28 weeks, Fetus is 100% viable.

Q. 15 The most common cause of first-trimester abortion is:

 A

Chromosomal defect

 B

Endocrine disturbances

 C

Anatomic abnormality of the uterus

 D

Infections

Ans. A

Explanation:

Ans. is A. i.e. Chromosomal defect

Fetal factors: 

  • Chromosomal abnormalities (M/C first trimester cause)
  • Hydropic degeneration of villi
  • twin/multiple pregnancies

Maternal factors

  • Maternal infections: TORCH infections, Malaria, Ureaplasma, Chlamydia, Brucella, Spirochaetes
  • Maternal medical disorders: Hypertension, Chronic renal disease, Cyanotic heart disease, Hemoglobinopathies.
  • Environmental factors: Alcohol, Smoking (leads to early pregnancy loss), Caffeine
  • Exposure to radiation: (> 5 rads) and anesthetic gases.
  • Endocrine problems: Luteal phase defect (deficiency of progesterone), Thyroid abnormalities – hypothyroidism, Poorly controlled diabetes mellitus, PCOD, Hyperprolactinemia
  • Immunological causes: Antiphospholipid antibody syndrome (APLA syndrome), Inherited thrombophilias
  • Uterine factors like Cervical incompetence (M/C 2nd trimester), Mullerian anomalies (M/C associated with abortions is the septate uterus), Large and multiple submucous leiomyomas, Asherman syndrome, DES exposure in utero.
  • Weight of mother: Underweight or nutritional deficiency does not lead to abortion, Obesity leads to abortion.
  • Others: Trauma, Subchorionic hematoma Defective placentation.

Paternal factors: Increased paternal age is associated with increased abortion.


Q. 16

The most common cause of second-trimester abortion:

 A

Chromosomal defect

 B

Cervical incompetence

 C

Abnormality of uterus

 D

Infections

Ans. B

Explanation:

Ans. Cervical incompetence

Fetal factors: 

  • Chromosomal abnormalities (M/C cause)
  • Hydropic degeneration of villi
  • twin/multiple pregnancies

Maternal factors

  • Maternal infections: TORCH infections, Malaria, Ureaplasma, Chlamydia, Brucella, Spirochaetes
  • Maternal medical disorders: Hypertension, Chronic renal disease, Cyanotic heart disease, Hemoglobinopathies.
  • Environmental factors: Alcohol, Smoking (leads to early pregnancy loss), Caffeine
  • Exposure to radiation: (> 5 rads) and anesthetic gases.
  • Endocrine problems: Luteal phase defect (deficiency of progesterone), Thyroid abnormalities – hypothyroidism, Poorly controlled diabetes mellitus, PCOD, Hyperprolactinemia
  • Immunological causes: Antiphospholipid antibody syndrome (APLA syndrome), Inherited thrombophilias
  • Uterine factors like Cervical incompetence (M/C 2nd trimester), Mullerian anomalies (M/C associated with abortions is the septate uterus), Large and multiple submucous leiomyomas, Asherman syndrome, DES exposure in utero.
  • Weight of mother: Underweight or nutritional deficiency does not lead to abortion, Obesity leads to abortion.
  • Others: Trauma, Subchorionic hematoma Defective placentation.

Paternal factors: Increased paternal age is associated with increased abortion.


Q. 17

The most common cause of early abortion –

 A

Genetic

 B

Maternal

 C

Immunologic

 D

Anatomic abnormalities

Ans. A

Explanation:

Ans. is A. i.e. Genetic

Causes of abortion

Fetal factors: 

  • Chromosomal abnormalities (M/C cause)
  • Hydropic degeneration of villi
  • twin/multiple pregnancies

Maternal factors

  • Maternal infections: TORCH infections, Malaria, Ureaplasma, Chlamydia, Brucella, Spirochaetes
  • Maternal medical disorders: Hypertension, Chronic renal disease, Cyanotic heart disease, Hemoglobinopathies.
  • Environmental factors: Alcohol, Smoking (leads to early pregnancy loss), Caffeine
  • Exposure to radiation: (> 5 rads) and anesthetic gases.
  • Endocrine problems: Luteal phase defect (deficiency of progesterone), Thyroid abnormalities – hypothyroidism, Poorly controlled diabetes mellitus, PCOD, Hyperprolactinemia
  • Immunological causes: Antiphospholipid antibody syndrome (APLA syndrome), Inherited thrombophilias
  • Uterine factors like Cervical incompetence (M/C 2nd trimester), Mullerian anomalies (M/C associated with abortions is the septate uterus), Large and multiple submucous leiomyomas, Asherman syndrome, DES exposure in utero.
  • Weight of mother: Underweight or nutritional deficiency does not lead to abortion, Obesity leads to abortion.
  • Others: Trauma, Subchorionic hematoma Defective placentation.

Paternal factors: Increased paternal age is associated with increased abortion.


Q. 18

A lady is 18 weeks pregnant and has a history of two times mid-trimester abortion, which was painless. What is the diagnosis?

 A

Incompetent os

 B

Chromosomal abnormality

 C

Bivalve uterus

 D

Progesterone deficiency

Ans. A

Explanation:

Ans.A. Incompetent os

The most common cause of second-trimester pregnancy loss is cervical incompetence, in which the patient presents with recurrent painless abortion.

Causes of abortion

Fetal factors: 

  • Chromosomal abnormalities (M/C cause).
  • Hydropic degeneration of villi.
  • twin/multiple pregnancies.

Maternal factors

  • Maternal infections: TORCH infections, Malaria, Ureaplasma, Chlamydia, Brucella, Spirochaetes.
  • Maternal medical disorders: Hypertension, Chronic renal disease, Cyanotic heart disease, Hemoglobinopathies.
  • Environmental factors: Alcohol, Smoking (leads to early pregnancy loss), Caffeine.
  • Exposure to radiation: (> 5 rads) and anesthetic gases.
  • Endocrine problems: Luteal phase defect (deficiency of progesterone), Thyroid abnormalities – hypothyroidism, Poorly controlled diabetes mellitus, PCOD, Hyperprolactinemia.
  • Immunological causes: Antiphospholipid antibody syndrome (APLA syndrome), Inherited thrombophilias.
  • Uterine factors like Cervical incompetence (M/C 2nd trimester), Mullerian anomalies (M/C associated with abortions is the septate uterus), Large and multiple submucous leiomyomas, Asherman syndrome, DES exposure in utero.
  • Weight of mother: Underweight or nutritional deficiency does not lead to abortion, Obesity leads to abortion.
  • Others: Trauma, Subchorionic hematoma Defective placentation.

Paternal factors: Increased paternal age is associated with increased abortion.



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